1. Field of the Invention
The present invention relates to a paper feed mechanism ina recorder which forms a record on a record paper being fed.
2. Description of the Prior Art
A prior art recorder of this type has a paper pressing mechanism called a paper bail having a paper pressing roller for pressing a record paper which is fed along a platen.
If only a paper feed roller which is rotated in contact with the platen is provided the movement of the record paper would be unstable or the record paper would slightly float from the platen and noises are generated when the record paper is impacted. The paper pressing mechanism is provided to prevent such problems.
In the paper pressing mechanism called the paper bail, the roller is urged to the platen in a normal condition, and it is moved off the platen by a manipulation of an operator when the record paper is loaded and again urged to the platen after the record apper has been loaded.
An example of the recorder of such a structure is shown in FIGS. 1-4. Numeral 1 denotes a platen to a shaft 1a of which a pulley 2 is fixed.
A belt 3 spans between the pulley 2 and a pulley 5 which is mounted on a paper feed motor 4.
A paper feed roller 8 contacts the platen 1 which is a rotating paper feed member, and a record paper 6 is fed through a space between the platen 1 and the paper feed roller 8. Numeral 9 denotes a paper bail which is a paper pressing member for pressing the record paper to the platen 1. It has left and right arms 7a which are holding members, and pinch rollers 7 are rotatably held on a shaft 7b which extends between the arms 7a.
The record paper 6 is guided along the platen 1, passes through a record position 6a and is pressed by the rollers 7.
Intermediate portions of the arms 7a are pivotably supported by a shaft 11 to a frame 10 of the recorder, and lower ends of the arms 7a are linked to ends of levers 15 by a shaft 7c.
Spring 17 spans between the other ends of the levers 15 and the frame 10 so that a clockwise rotating force is imparted to the lever 15.
Numeral 13 denotes a release lever for actuating the paper bail. An intermediate portion therof is pivotably supported by a shaft 14 to the frame 10.
A pin 16 projects from a lower end of the release lever 13 and fits into a notch 15a formed below a free end of the lever 15.
A torsion coil spring 12 which functions as an overcenter spring spans between a projection formed near a bearing of the arm 7a and the frame 10.
In the recorder thus constructed, the release lever 13 is rotated clockwise as shown in FIG. 3 and the lever 15 is pushed leftward. Accordingly, the arm 7a is rotated clockwise around the shaft 11 and the roller 7 pushes the platen 1.
On the other hand, in the release mode, the release lever 13 is rotated counterclockwise as shown in FIG. 4, the lever 15 is pulled rightward through the pin 16 and the arm 7a is moved off the platen 1. Accordingly, the roller 7 is moved off the platen 1.
Under this condition, the torsion coil spring 12 is beyond its deadpoint and the lower end of the arm 7a holds the arm 7a at a position in contact with a stopper 10a projecting from a side of a frame 10.
By manipulating the release lever 13, the contact and the separation of the platen and the roller are attained.
As various types of recorders are designed, a so-called cut sheet feeder which is detachable from the recorder and automatically feeds and ejects a record paper is used.
FIG. 5 shows a recorder having such a cut sheet feeder mounted. Numeral 18 denotes a paper stacker of the cut sheet feeder which accommodates a number of record papers and is urged to a paper feed roller 20 made of rubber by a spring 19 through the record paper.
The paper feed roller 20 is rotated by a separate drive source 9 (not shown) to feed the record papers, one at a time, to the platen 1 through a space between paper guides 21 and 22.
The record paper fed out of the paper guides 21 and 22 is fed to a space between the platen 1 and the paper feed roller 8 which normally contacts the platen 1 and fed in a print direction.
A gear 1a is fixed to the shaft 1a of the platen 1 and rotated by a drive source (not shown). A gear 23 which is a motive force transmission member meshes with the gear 1a, and a gear 24 meshes with the gear 23, a paper ejection roller 25 which is a rotating member is fixed to a shaft of the gear 24, and a pinch roller 26 contacts the roller 25. Numeral 27 denotes a paper guide which is in union with an ejection stacker 28 which accommodates the record papers fed out of the platen 1.
The record paper 6 is fed into the ejection stacker 28 through a space between the paper ejection roller 25 and the pinch roller 26 which is urged to the roller 26 by a spring (not shown).
The feed amount by the paper ejection roller 25 and the feed amount by the platen 1 are set to be equal and the roller 25 and the platen 1 are rotated synchronously.
When the cut sheet feeder of this structure is mounted, the following disadvantage is encountered.
The automatically fed record paper may jam if the paper bail 9 contacts the platen 1 in the apparatus having the cut sheet feeder mounted thereon. Accordingly, the paper bail 9 is released when the cut sheet feeder is used, and the rollers 25 and 26 take the place of the rollers of the paper bail 9.
However, when the paper bail 9 is in the released position, the rollers 7 of the paper bail block a view field of an operator so that the operator cannot watch the record position.